Gender Differences in Water-Based Aerobic Capacity During Freestyle Swimming to Exhaustion

Abstract

Aerobic capacity plays an essential role in physical performance. Females have been shown to have lower aerobic capacity during land-based incremental testing when compared to their male counterparts. However, there have been few studies on gender differences in aerobic capacity during water-based incremental swimming. Understanding the gender differences is an important step in coaching/training. PURPOSE: The purpose of this study was to examine aerobic capacity gender differences. METHODS: A total of 15 males (23.6±6.7yrs, 179.3±6.4cm, 75.2±11.5kg) and 15 females (22.6±6.3yrs, 167.6±6.4cm, 65.7±9.5kg) participated in the study and completed an incremental swimming test to exhaustion. The protocol involved swimming a minimum of 250 meters (10 lengths) using the freestyle stroke. Rest periods following each 22.9 meter length decreased from 10 seconds to 3 seconds throughout the test. Following 9 lengths, subjects continuously swam at maximal velocity until VO2max had been achieved or until exhaustion occurred. Aerobic capacity was measured with a portable metabolic system suspended above the swimmer using a cable pulley system, enabling a standard freestyle stroke with continuous measure of VO2. Ratings of perceived exertion (RPE), blood lactate (BLa), and maximal heart rate (HRmax) were also measured at the end of the test. Data were tested for normality, and independent samples t-tests or Mann–Whitney U tests were used, as appropriate (p<0.05). RESULTS: Males had significantly higher aerobic capacity (males: 48.4±7.4ml/kg/min, females: 39.8±5.3ml/kg/min, p=0.001) and lower HRmax (males: 173.3±6.9bpm, females: 180.7±7.7bpm, p=0.032) compared to females. There were no gender differences in RPE (males: 9.6±0.7, females: 9.5±0.7, p=0.689) or BLa (males: 11.3±3.5mmol/L, females: 9.9±2.9mmol/L, p=0.269). CONCLUSIONS: The current results have revealed significant gender differences in aerobic capacity at the maximal effort (with similar RPE scale and BLa values). These findings are in accordance with other land-based gender studies on aerobic capacity, largely due to smaller stature/lung in females. Future studies should examine the effects of gender-specific and customized land/water-based training on their aerobic capacity. Supported by ONR: N00014-14-1-0022/N00014-15-0069